High-temperature vat dyeing baths using trialkanolamines



Patented July 13, 1954 HIGH-TEMPERATURE VAT DYEING BATHS USING TRIALKANOLAMINES Jerry M. Mecco, Somerviile, N. 3., assignor to American Cyanamid Company, New York, N. Y.,

a corporation of Maine No Drawing. Application November 1, 1952,

Serial No. 318,337

16 Claims.

This invention relates to improved reduction baths containing alkali metal hydrosulfite and over-reduction buffers and the compositions for producing them.

In ordinary vat dyeing there is used a reduction bath to transform the vat dye into its leuco form. This reduction bath is strongly alkaline and for the reducing material generally uses a metal hydrosulfite, usually sodium or zinc hydrosulfite. Numerous vat dyes in past have shown themselves sensitive to over-reduction in dyeing at elevated temperatures. This constituted a serious drawback in the case of the sensitive dyes as there is a great economic advantage in dyeing at high temperature. In my prior patents, Nos. 2,548,543 and 2,548,544, both dated April 10, 1951, and in my Patent No. 2,576,846, dated November 27, 1951, I have described processes for the high temperature dyeing of vat dyestuffs which are sensitive to over-reduction using certain over-reduction bufiers. In the two patents dated April 10, 1951, the inorganic nitrites and halogenates are described and claimed, and in my Patent No. 2,576,846, dated November 27, 1951, organic nitrogen compounds in which the nitrogen is attached by at least one covalent bond to oxygen and by at least one covalent bond to an element other than oxygen or nitrogen are, described and claimed. These compounds stabilized the dyestuffs and prevented over-reduction. The same compounds were also found to improve the dyeing with certain pyranthrone vatdyestuffs which are not sensitive to over-reduction. Processes using nitrites and halogenates in the dyeing of these pyranthrone dyes are described and claimed. in my prior patents Nos. 2,548,545. and 2,548,546, both issued April 10, 1951, while in my Patent No. 2,576,847, dated November 27, 1951, the use of the organic nitrogen compounds referred to above is described and claimed in the dyeing of the pyranthrone dyes.

The stabilizing agents or over-reduction buffers described solve the problem presented by over-reduction of sensitive vat dyestuffs in high temperature dyeing and improve the dyeing of the pyranthrone dyestuffs referred to above. However, this greatly improved result was obtained at the expense of increased hydrosulfite consumption and while the. consumption of hydrosulfite is not so great as to render the improved dye or processes uneconomical, the cost of the increased hydrosulfite consumption is nevertheless sufficient so that reduction of the excessive consumption is economically desirable.

The mechanism which results in increased hydrosulfite consumption is not fully determined, but appears to be due, at least in part, to chemical reaction with the stabilizer or over-reduction buffer.

According to the present invention, I have found excessive consumption of hydrosulfite can be markedly reduced by the incorporation of, a small amount of trialkanolamine. As-little as .01 percent based on the alkali metal hydrosulfite results in marked reduction of the hydrosulfite consumption at high temperatures. The effect becomes even more marked as the amount of triallranolamine is increased, but when the amount of trialkanolamine reaches 1.0 percent of the hydrosulfite no further material improvement re sults from the use of more trialkanolamine.

The preparation of baths has been described above in terms of. adding an ingredient to the bath. In many cases this is preferable, but it is also possible to produce compositions containing the vat dyestuff and the trialkanolamine. Such compositions contain suificient trialkanolamine so that when a vat dye bath is prepared inthe normal manner the trialkanolamine counteracts the hydrosulfite consumption. Thus it is possible to market a composition which can be used without any measurement of other ingredients to produce the dyebaths of the present invention.

The over-reduction buffers are substantial equivalents and the present invention is therefore applicable, regardless of whether there is a single buffer present or a mixture of two or moreof them.

It is also possible to use the trialkanolamines of the present invention with other stabilizers, such as magnesium or manganese compounds. These other stabilizers are not claimed in the present application, but form the subject matter respectively of my copending application, Serial No. 258,282, filed November 26, 1951, and the copending application of Frederick Fordemwalt, Serial No. 258,280, filed November 26, 1951, both now abandoned.

The operation of the present invention is not limited to vat dyeing baths in which the vat dye is actually incorporated into the bath. Similar savings in hydrosulfite consumption are obtainable when the bath contains only the stabilizing agent or over-reduction bufier and the hydrosulfite, as in the case of certain pigment dyeing processes.

The invention will be described in greater detail in conjunction with the following specific examples, the parts being by weight unless otherwise specified.

Example 1 A bath containing 4 oz./gal NaOH, 2 oz./ga'l. NaClO; and 0.01 oz./gal. of triethanolamine was heated to appromixately 200 F. and 4 oz./gal. of Na2S2O4 were added.

The rate of hydrosulfite consumption, as measured by titration with a standard indigo solution, was approximately 0.11 oz./gal./min. The consumption of hydrosulfite was about twice as fast, 1. e., 0.22 oz./gal./min., in a corresponding bath which contained no triethanolamine.

Example 2 The method described in Example 1 was repeated with hydroxylammonium sulfate in stead of NaClOa in the bath. The hydrosulfite consumption was only about one-third as rapid in the presence of the triethanolamine as it was when none of the triethanolamine was present.

Example 3 In a test run as described in Example 1 with 0.04 oz./gal. of a commercial paste of the blue vat dye having Colour Index No. 1113 also present in the bath, the hydrosulfite consumption was less than half as rapid in the bath which contained the triethanolamine as in the bath in which no triethanolamine had been added.

After 27 minutes, swatches of 80 x 80 bleached cotton cloth were added to the two baths and dyed for 10 minutes. A good blue dyeing was obtained in the bath which had the triethanolamine present whereas, without the triethanolamine, only a weak tint entirely unsatisfactory for commercial use was obtained.

Example 4 The method of Example 3 was repeated with hydroxylammonium sulfate used instead of NaCIOa. The hydrosulfite consumption was less than one-third as rapid in the presence of the triethanolamine as it was in the bath containing no triethanolamine.

Example 5 A dye bath containing 0.3 oz./gal, of a commercial paste of the blue vat dye having Colour Index No. 1113, 2.0 oz./gal. NaOH, 0.5 oz./gal. NaNOz, 2.0 oz./gal. Na2S2O4 and 1.0 oz./gal. triethanolamine was heated to a temperature of 200 F. and held at that temperature for 30 minutes. The bath remained in reduction throughout and at the end of the period the bath still contained about 0.8 oz./gal. of NazS2O4.

In a similar bath except that it contained no triethanolamine, the hydrosulfite was consumed and the dye precipitated in the bath within 15 minutes.

Example 6 A dye bath containing 0.1 oz./gal. of a com bath still contained 0.8 oz./gal. of Na2SzO4 and the yarn was dyed a satisfactory shade.

An attempt to carry out the dyeing in a bath similar in all respects except that there was no triethanolamine present was unsuccessful because the hydrosulfite was entirely consumed at the end of 5 minutes and the dye no longer remained in reduction.

Example 7 A series of five baths was prepared and heated to a temperature of approximately 200 F. Each bath contained 0.3 oz./gal. of a commercial paste of the blue vat dye having Colour Index No. 1113, 4 oz./ga1. NaOH, 4 oz./gal. Na-2s2o4, and 1 oz./gal. NaNOz. Titrations with a standard indigo solution were made at intervals to determine the amounts of sodium hydrosulfite in the baths.

In No. 1, which contained no additional material, the hydrosulfite was consumed in five minutes.

In No. 2, which contained 0.25 oz./gal. of triethanolamine, the hydrosulfite lasted for approximately twenty minutes.

In No. 3, which contained 1.0 oz./gal, of triethanolamine, the hydrosulfite lasted for approximately thirty minutes.

In Nos. 4 and 5, which contained 2 oz./ al. and 4 0z./ga1. respectively of triethanolamine, there was still approximately 0.8 oz./gal. of hydrosulfite present after thirty minutes heating.

A series of baths like bath No. l, i. e., no triethanolamine present, described above was prepared and each was heated to a different temperature. The consumption of hydrosulfite in each was observed by titrations with standard indigo solution. The times required for the hydrosulfite to be consumed depended upon the temperature of the bath as shown by the following:

'lime Required for the Hy- (Not consumed in 1 hour.) Approx. 20 minutes. 4 Approx. 10 minutes. Approx. 7 minutes. Approx. 5 minutes.

Thus, it may be seen that with only 1 oz./gal. of triethanolamine in the bath, the hydrosulfite consumption at 200 F. was less than at 140 F. in a similar bath with no triethanolamine present.

Example 8 When the method described in Example 5 was repeated with a commercial paste of the vat dye made according to U. S. Patent No. 2,456,589 instead of the blue dye, the results were essentially the same as described in Example 5.

Example 9 Two dye baths were set up, each containing 4 oz./gal. of NaOH, 1 0z./gal. of NaNOz, 0.1 oz./gal. of a commercial paste of the blue vat dye having Colour Index No. 1113, and 4 oz./ga1. of zinc hydrosulfite. One of thebaths contained, in addition, 0.04 oz./gal. of triethanolamine.

Titrations with standard indigo showed that, in the bath which did not contain the triethanolamine, the hydrosulfite consumption was about more rapid than it was in the other bath in which the triethanolamine was present.

Example 10 The procedure of Example 5 was repeated using the tri-iso-propanolamine instead of triethanolamine. The results were substantially the same.

Example 11 The procedure of Example 1 was repeated substituting a corresponding amount-of tri-isopropanolamine for the triethanolamine. The results were substantially the same.

Example 12' A dyebath was prepared. to contain 4 oz./gal. NaOH, 0.03 oz./gal. of a commercial paste of the blue vat dye having Colour Index No. 1113, 1.0 'oz./gal. NaNOz, 4 oz./gal. sodium hydrosulfite, 0.003 oz./gal. triethanolamine, 0.003. oz./ga1: hydrated magnesium sulfate, 0.0.03 02/ gal. hydrated manganese chloride.

When this bath, along with a corresponding bath containing no magnesium, manganese; or triethanolamine was held at. a temperature of 200 F., the hydrosulfite consumption was about three times as rapid in the unprotected 'bathas it was in that which contained the magnesium, manganese, and triethanolamine.

Example 13 500 parts of a vat dye press cake containing 100 parts of the real dye having Colour Index No. 1112 were dispersedwith 5. parts of disodium disulfodinaphthylmethane. Approximately 100 parts of water were then evaporated from the dye dispersion and replaced with 100 parts of triethanolamine. After passing through a highspeed mixer, this paste was used in making a dyeing by the procedure of Example 3, except no additional triethanolamine was added. A good blue dyeing was obtained, whereas in a similar dyeing made by using the vat dye having Colour Index No. 1112 with no triethanolamine added to the dye bath, a dyeing entirely unsatisfactory for commercial use was obtained.

Example 14 The procedure of the preceding example was repeated as follows:

Water Evaporated and Replaced with Triethanol-amine Press Cake Used Parts 500 parts C. I. No. 11l2 Do 500 parts 0. I. No. 1113. 500 parts 0. I. No. 500 parts 0. I. No.

a'seaee Dyeings were made on bleached cotton and viscose rayon by the procedure of Example 3 and the results were similar to those obtained in Example 3. However, it was noticed that the dyeing made from the paste containing only arts of the amine was slightly inferior to the dyeing made from the paste containing 80 parts.

Example 15 The procedure of Example 13 was repeated using the dye 6,6'-di-chloro-4,4'-dimethyl-2,2- bis(thio) naphthene indigo. When this paste was dyed by the procedure of Example 13, a commercially satisfactory product was obtained.

Example 16 Example 17 The procedure of the preceding example was repeated except the dye having Colour Index No. 1113 was used. The dyed cellulosic material was commercially acceptable.

Eanample 18 The dye having Colour Index No. 1106' was colloidized by the procedure outlined in "Example 16 and then dyed by the procedure of Example 13 and a solid blue shade was obtained.

. shade was obtained.

Example 20 The dye of Example 18. was colloidized byv the procedure outlined. in Example 16, except parts of triethanolamine hydrochloride were used. instead of'100. parts as in Example 16. The results were similar to those obtained in Examp e. 16.

Example 21 The dye bath was prepared to contain 0.5 part of a commercial paste of the vat dye having Colour Index No. 1113 and containing 0.1 part real dye, 6.0 parts of NaOH, 1.5 parts of NaNOz and 200.0 parts of water. The bath was heated to approximately 200 F. and held at that temperature. 6.0 parts of NazS2O4 were added and the bath stirred frequently.

Titrations with a standard indigo solution of soluble indigo showed that after 10 minutes the sodium hydrosulfite had all been consumed.

In a similar bath to which had been added the equivalent of 0.28 part of triethanolamine, the hydrosulfite consumption was much less, there still being 4 parts of hydrosulfite present in the bath after 11 minutes.

In a third bath prepared like the first except that there were added to the bath 0.24 part of triethanolamine and 0.078 part of potassium permanganate, there were still approximately 3.5 parts of hydrosulfite remaining in the bath at the end of 12 minutes.

Example 22 A dye bath was prepared to contain 4 oz./ gal. of NaOI-I and 2 oz./gal. of hydroxylammonium sulfate. The bath was heated to approximately 200 F. and held at that temperature. 4 oz./gal. of Na2SzO4 were then added and the bath stirred frequently. At the end of 20 minutes a titration with a standard solution of soluble indigo showed that less than 0.4 oz./gal. of the hydrosulfite remained in the bath.

In a second bath, like the above except that 0.02 oz./gal. of triethanolamine had been added, more than twice as much hydrosulfite remained after the same period of heating.

I claim:

1. A reducing bath suitable for high temperature vat dyeing comprising an aqueous solution of caustic alkali and metal hydrosulfite, a stabilizer against over-reduction of vat dyes selected from the group consisting of inorganic nitrites, inorganic halogenates and nitrogen compounds in which a nitrogen atom is attached by at least one co-valent bond to oxygen and at least one co-valent bond to an element other than oxygen or nitrogen and at least 0.1% of a lower trialkanolamine based on the weight of the hydrosulfite.

2. A bath according to claim 1 containing a vat dyestufi capable of over-reduction at elevated temperature.

3. A bath according to claim 2 in which the lower trialkanolamine is triethylanolamine.

4. A bath according to claim 1 in which the lower trialkanolamine is triethanolamine.

5. A bath according to claim 4 containing a pyranthrone vat dyestuff.

6. A bath according to claim 4 in which the stabilizer is alkali metal nitrite.

7. A bath according to claim 3 in which the stabilizer is alkali metal nitrite.

8. A bath according to claim 3 in which the vat dyestuil is a vat dyestuff of the indanthrone series.

9. A bath according to claim 8 in which the stabilizer is alkali metal nitrite.

10. A bath according to claim 3 in which the stabilizer is a nitrogen compound linked by at least one co-valent bond to oxygen and by at least one co-valent bond to an atom other than oxygen or nitrogen.

11. A bath according to claim 10 in which the vat dyestufi is a dyestufi of the indanthrone series.

12. A bath according to claim 3 in which the stabilizer is an inorganic halogenate.

13. A bath according to claim 1 in which the stabilizer against over-reduction is a hydroxylamine compound.

14. A bath according to claim 13 containing a vat dyestufi capable of over-reduction at elevated temperatures.

15. A bath according to claim 1 in which the lower trialkanolamine is associated with at least one compound of a metal selected from the group consisting of magnesium and manganese.

16. A bath according to claim 15 containing a vat dyestufi capable of over-reduction at elevated temperatures.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,782,122 Kern Nov. 18, 1930 FOREIGN PATENTS Number Country Date 324,315 Great Britain Jan. 16, 1930 

1. A REDUCING BATH SUITABLE FOR HIGH TEMPERATURE VAT DYEING COMPRISING AN AQUEOUS SOLUTION OF CAUSTIC ALKALI AND METAL HYDROSULFITE, A STABILIZER AGAINST OVER-REDUCTION OF VAT DYES SELECTED FROM THE GROUP CONSISTING OF INORGANIC NITRITES, INORGANIC HALOGENATES AND NITROGEN COMPOUNDS IN WHICH A NITROGEN ATOM IS ATTACHED BY AT LEAST ONE CO-VALENT BOND TO OXYGEN AND AT LEAST ONE CO-VALENT BOND TO AN ELEMENT OTHER THAN OXYGEN OR NITROGEN AND AT LEAST 0.1% OF A LOWER TRIALKANOLAMINE BASED ON THE WEIGHT OF THE HYDROSULFITE. 